Push product_compatible_with_current_order and available_distributors_for down to DistributorChangeValidator, add tests

app/helpers/add_to_cart_helper.rb

@@ -4,16 +4,10 @@ module AddToCartHelper
   end
 
   def product_incompatible_with_current_order(order, product)
-    order.present? && available_distributors_for(order, product).empty?
+    !DistributorChangeValidator.new(order).product_compatible_with_current_order(product)
   end
 
   def available_distributors_for(order, product)
-    distributors = Enterprise.distributing_product(product)
-
-    if order && order.distributor
-      distributors = DistributorChangeValidator.new(order).available_distributors(distributors)
-    end
-
-    distributors
+    DistributorChangeValidator.new(order).available_distributors_for(product)
   end
 end

lib/open_food_web/distributor_change_validator.rb

@@ -14,6 +14,20 @@ class DistributorChangeValidator
     @order.line_items.empty? || (available_distributors(Enterprise.all) || []).include?(distributor)
   end
 
+  def product_compatible_with_current_order(product)
+    @order.nil? || available_distributors_for(product).present?
+  end
+
+  def available_distributors_for(product)
+    distributors = Enterprise.distributing_product(product)
+
+    if @order.andand.line_items.present?
+      distributors = available_distributors(distributors)
+    end
+
+    distributors
+  end
+
   def available_distributors enterprises
     enterprises.select do |e|
       (@order.line_item_variants - e.distributed_variants).empty?

spec/lib/open_food_web/distributor_change_validator_spec.rb

@@ -3,7 +3,8 @@ require 'open_food_web/distributor_change_validator'
 describe DistributorChangeValidator do
   let(:order) { double(:order) }
   let(:subject) { DistributorChangeValidator.new(order) }
-  
+  let(:product) { double(:product) }
+
   context "permissions for changing distributor" do
     it "allows distributor to be changed if line_items is empty" do
       order.stub(:line_items) { [] }
@@ -84,4 +85,47 @@ describe DistributorChangeValidator do
       subject.available_distributors([]).should == []
     end
   end
+
+  describe "checking product compatibility with current order" do
+    it "returns true when order is nil" do
+      subject = DistributorChangeValidator.new(nil)
+      subject.product_compatible_with_current_order(product).should be_true
+    end
+
+    it "returns true when there's an distributor that can cover the new product" do
+      subject.stub(:available_distributors_for).and_return([1])
+      subject.product_compatible_with_current_order(product).should be_true
+    end
+
+    it "returns false when there's no distributor that can cover the new product" do
+      subject.stub(:available_distributors_for).and_return([])
+      subject.product_compatible_with_current_order(product).should be_false
+    end
+  end
+
+  describe "finding available distributors for a product" do
+    it "returns enterprises distributing the product when there's no order" do
+      subject = DistributorChangeValidator.new(nil)
+      Enterprise.stub(:distributing_product).and_return([1, 2, 3])
+      subject.should_receive(:available_distributors).never
+
+      subject.available_distributors_for(product).should == [1, 2, 3]
+    end
+
+    it "returns enterprises distributing the product when there's no order items" do
+      order.stub(:line_items) { [] }
+      Enterprise.stub(:distributing_product).and_return([1, 2, 3])
+      subject.should_receive(:available_distributors).never
+
+      subject.available_distributors_for(product).should == [1, 2, 3]
+    end
+
+    it "filters by available distributors when there are order items" do
+      order.stub(:line_items) { [1, 2, 3] }
+      Enterprise.stub(:distributing_product).and_return([1, 2, 3])
+      subject.should_receive(:available_distributors).and_return([2])
+
+      subject.available_distributors_for(product).should == [2]
+    end
+  end
 end